feat(server): add brand kit management and project binding

Add a brand kit domain with memory and postgres stores, a BrandKitService
for CRUD and resolution, and REST endpoints to list, upsert, and delete
brand kits. Projects can bind a brand kit whose resolved context and
reference images feed into the agent's long-term memory and design prompts.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

server/internal/infrastructure/piagent/design_agent.go

@@ -210,7 +210,7 @@ func directImagePlan(req design.AgentRequest) design.AgentPlan {
 
 func directImagePrompts(req design.AgentRequest) []design.AgentImagePrompt {
 	count := plannedGenerationCount(req)
-	prompt := strings.TrimSpace(req.Prompt)
+	prompt := directImagePrompt(req)
 	if prompt == "" {
 		prompt = fallbackDirectImagePrompt(req)
 	}
@@ -257,7 +257,7 @@ func directImageTasksSharePrompt(req design.AgentRequest) bool {
 }
 
 func directImageBatchPrompt(req design.AgentRequest) design.AgentImagePrompt {
-	prompt := strings.TrimSpace(req.Prompt)
+	prompt := directImagePrompt(req)
 	if prompt == "" {
 		prompt = fallbackDirectImagePrompt(req)
 	}
@@ -614,6 +614,12 @@ func referenceImageURLs(req design.AgentRequest) []string {
 			}
 		}
 	}
+	for _, image := range req.Project.BrandImages {
+		add(image)
+		if len(urls) >= 16 {
+			return urls[:16]
+		}
+	}
 	if len(urls) > 16 {
 		return urls[:16]
 	}
@@ -662,9 +668,9 @@ func fallbackImagePrompt(req design.AgentRequest, index int) string {
 		task := req.TaskPlan.ImageTasks[index]
 		if brief := strings.TrimSpace(task.Brief); brief != "" {
 			if title := strings.TrimSpace(task.Title); title != "" && !strings.Contains(brief, title) {
-				return title + ": " + brief
+				return imagePromptWithBrandKit(title+": "+brief, req)
 			}
-			return brief
+			return imagePromptWithBrandKit(brief, req)
 		}
 	}
 	return fallbackDirectImagePrompt(req)
@@ -1064,6 +1070,9 @@ func fallbackDirectImagePrompt(req design.AgentRequest) string {
 	if brief := strings.TrimSpace(req.Project.Brief); brief != "" {
 		lines = append(lines, "Project brief: "+truncateRunes(brief, 180))
 	}
+	if brandContext := strings.TrimSpace(req.Project.BrandContext); brandContext != "" {
+		lines = append(lines, "Binding Brand Kit: "+truncateRunes(brandContext, 520))
+	}
 	if memory := compactFallbackMemory(req.Memory); memory != "" {
 		lines = append(lines, "Relevant memory: "+memory)
 	}
@@ -1080,6 +1089,19 @@ func fallbackDirectImagePrompt(req design.AgentRequest) string {
 	return compactImageGenerationPrompt(strings.Join(lines, "\n"), imageGenerationFallbackMaxRunes)
 }
 
+func directImagePrompt(req design.AgentRequest) string {
+	return imagePromptWithBrandKit(req.Prompt, req)
+}
+
+func imagePromptWithBrandKit(prompt string, req design.AgentRequest) string {
+	prompt = strings.TrimSpace(prompt)
+	brandContext := strings.TrimSpace(req.Project.BrandContext)
+	if brandContext == "" {
+		return prompt
+	}
+	return strings.TrimSpace(prompt + "\n\nBinding Brand Kit requirements:\n" + brandContext)
+}
+
 func compactFallbackMemory(memory design.AgentMemory) string {
 	if memory.IsZero() {
 		return ""